PHP Date / Time Problem

So I'm trying to get the difference in days for the following dates. For one of them it works, but for the other the number is off. It should be 3.

I could use the ceil function, but I still don't know why the following isn't correct.

$checkOut = strtotime('2011-02-16');
$checkIn = strtotime('2011-02-11');
echo ($checkOut - $checkIn) / (60 * 60 * 24); // => 5
echo f开发者_开发知识库loor(($checkOut - $checkIn)/(60*60*24)); // => 5

$checkOut = strtotime('2011-03-14');
$checkIn = strtotime('2011-03-11');
echo ($checkOut - $checkIn) / (60 * 60 * 24); // => 2.958333333
echo floor(($checkOut - $checkIn)/(60*60*24)); // => 2

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Why not use the php object-oriented DateTime::diff?

<?php
$datetime1 = new DateTime('2011-03-11');
$datetime2 = new DateTime('2011-03-14');
$interval = $datetime1->diff($datetime2);
echo $interval->format('%R%a days');

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You may want to use DateTime::diff() for that problem.

By using floor() you're essentially getting the next lower integer (cutting away everything after the comma).

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So the problem is because it crosses daylight savings time. Although the PHP spec says that strtotime returns seconds since epoch, I guess that is not the case.